rustc_metadata: remove Encodable requirements from LazyMeta impls.

Author: eddyb

src/librustc_metadata/rmeta/decoder.rs

@@ -32,7 +32,7 @@ use std::mem;
 use std::num::NonZeroUsize;
 use std::u32;
 
-use rustc_serialize::{Decodable, Decoder, Encodable, SpecializedDecoder, opaque};
+use rustc_serialize::{Decodable, Decoder, SpecializedDecoder, opaque};
 use syntax::attr;
 use syntax::ast::{self, Ident};
 use syntax::source_map::{self, respan, Spanned};
@@ -217,15 +217,15 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a CrateMetadata, TyCtxt<'tcx>) {
     }
 }
 
-impl<'a, 'tcx, T: Encodable + Decodable> Lazy<T> {
+impl<'a, 'tcx, T: Decodable> Lazy<T> {
     fn decode<M: Metadata<'a, 'tcx>>(self, metadata: M) -> T {
         let mut dcx = metadata.decoder(self.position.get());
         dcx.lazy_state = LazyState::NodeStart(self.position);
         T::decode(&mut dcx).unwrap()
     }
 }
 
-impl<'a: 'x, 'tcx: 'x, 'x, T: Encodable + Decodable> Lazy<[T]> {
+impl<'a: 'x, 'tcx: 'x, 'x, T: Decodable> Lazy<[T]> {
     fn decode<M: Metadata<'a, 'tcx>>(
         self,
         metadata: M,
@@ -324,13 +324,13 @@ impl<'a, 'tcx> TyDecoder<'tcx> for DecodeContext<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx, T: Encodable> SpecializedDecoder<Lazy<T>> for DecodeContext<'a, 'tcx> {
+impl<'a, 'tcx, T> SpecializedDecoder<Lazy<T>> for DecodeContext<'a, 'tcx> {
     fn specialized_decode(&mut self) -> Result<Lazy<T>, Self::Error> {
         self.read_lazy_with_meta(())
     }
 }
 
-impl<'a, 'tcx, T: Encodable> SpecializedDecoder<Lazy<[T]>> for DecodeContext<'a, 'tcx> {
+impl<'a, 'tcx, T> SpecializedDecoder<Lazy<[T]>> for DecodeContext<'a, 'tcx> {
     fn specialized_decode(&mut self) -> Result<Lazy<[T]>, Self::Error> {
         let len = self.read_usize()?;
         if len == 0 {

src/librustc_metadata/rmeta/encoder.rs

@@ -122,13 +122,13 @@ impl<'tcx> Encoder for EncodeContext<'tcx> {
     }
 }
 
-impl<'tcx, T: Encodable> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
+impl<'tcx, T> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
     fn specialized_encode(&mut self, lazy: &Lazy<T>) -> Result<(), Self::Error> {
         self.emit_lazy_distance(*lazy)
     }
 }
 
-impl<'tcx, T: Encodable> SpecializedEncoder<Lazy<[T]>> for EncodeContext<'tcx> {
+impl<'tcx, T> SpecializedEncoder<Lazy<[T]>> for EncodeContext<'tcx> {
     fn specialized_encode(&mut self, lazy: &Lazy<[T]>) -> Result<(), Self::Error> {
         self.emit_usize(lazy.meta)?;
         if lazy.meta == 0 {

src/librustc_metadata/rmeta/mod.rs

@@ -15,7 +15,6 @@ use rustc_target::spec::{PanicStrategy, TargetTriple};
 use rustc_index::vec::IndexVec;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
-use rustc_serialize::Encodable;
 use syntax::{ast, attr};
 use syntax::edition::Edition;
 use syntax::symbol::Symbol;
@@ -59,7 +58,7 @@ trait LazyMeta {
     fn min_size(meta: Self::Meta) -> usize;
 }
 
-impl<T: Encodable> LazyMeta for T {
+impl<T> LazyMeta for T {
     type Meta = ();
 
     fn min_size(_: ()) -> usize {
@@ -68,7 +67,7 @@ impl<T: Encodable> LazyMeta for T {
     }
 }
 
-impl<T: Encodable> LazyMeta for [T] {
+impl<T> LazyMeta for [T] {
     type Meta = usize;
 
     fn min_size(len: usize) -> usize {
@@ -124,13 +123,13 @@ impl<T: ?Sized + LazyMeta> Lazy<T> {
     }
 }
 
-impl<T: Encodable> Lazy<T> {
+impl<T> Lazy<T> {
     fn from_position(position: NonZeroUsize) -> Lazy<T> {
         Lazy::from_position_and_meta(position, ())
     }
 }
 
-impl<T: Encodable> Lazy<[T]> {
+impl<T> Lazy<[T]> {
     fn empty() -> Lazy<[T]> {
         Lazy::from_position_and_meta(NonZeroUsize::new(1).unwrap(), 0)
     }